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author | Florian Dold <florian.dold@gmail.com> | 2017-05-24 15:10:37 +0200 |
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committer | Florian Dold <florian.dold@gmail.com> | 2017-05-24 15:11:17 +0200 |
commit | 7a3df06eb573d36142bd1a8e03c5ce8752d300b3 (patch) | |
tree | 70bfaea8884c374876f607774850a3a51c0cb381 /node_modules/shelljs/src/head.js | |
parent | aca1143cb9eed16cf37f04e475e4257418dd18ac (diff) |
fix build issues and add typedoc
Diffstat (limited to 'node_modules/shelljs/src/head.js')
-rw-r--r-- | node_modules/shelljs/src/head.js | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/node_modules/shelljs/src/head.js b/node_modules/shelljs/src/head.js new file mode 100644 index 000000000..13d582977 --- /dev/null +++ b/node_modules/shelljs/src/head.js @@ -0,0 +1,104 @@ +var common = require('./common'); +var fs = require('fs'); + +common.register('head', _head, { + canReceivePipe: true, + cmdOptions: { + 'n': 'numLines', + }, +}); + +// This reads n or more lines, or the entire file, whichever is less. +function readSomeLines(file, numLines) { + var BUF_LENGTH = 64 * 1024; + var buf = new Buffer(BUF_LENGTH); + var bytesRead = BUF_LENGTH; + var pos = 0; + var fdr = null; + + try { + fdr = fs.openSync(file, 'r'); + } catch (e) { + common.error('cannot read file: ' + file); + } + + var numLinesRead = 0; + var ret = ''; + while (bytesRead === BUF_LENGTH && numLinesRead < numLines) { + bytesRead = fs.readSync(fdr, buf, 0, BUF_LENGTH, pos); + var bufStr = buf.toString('utf8', 0, bytesRead); + numLinesRead += bufStr.split('\n').length - 1; + ret += bufStr; + pos += bytesRead; + } + + fs.closeSync(fdr); + return ret; +} +//@ +//@ ### head([{'-n': \<num\>},] file [, file ...]) +//@ ### head([{'-n': \<num\>},] file_array) +//@ Available options: +//@ +//@ + `-n <num>`: Show the first `<num>` lines of the files +//@ +//@ Examples: +//@ +//@ ```javascript +//@ var str = head({'-n': 1}, 'file*.txt'); +//@ var str = head('file1', 'file2'); +//@ var str = head(['file1', 'file2']); // same as above +//@ ``` +//@ +//@ Read the start of a file. +function _head(options, files) { + var head = []; + var pipe = common.readFromPipe(); + + if (!files && !pipe) common.error('no paths given'); + + var idx = 1; + if (options.numLines === true) { + idx = 2; + options.numLines = Number(arguments[1]); + } else if (options.numLines === false) { + options.numLines = 10; + } + files = [].slice.call(arguments, idx); + + if (pipe) { + files.unshift('-'); + } + + var shouldAppendNewline = false; + files.forEach(function (file) { + if (!fs.existsSync(file) && file !== '-') { + common.error('no such file or directory: ' + file, { continue: true }); + return; + } + + var contents; + if (file === '-') { + contents = pipe; + } else if (options.numLines < 0) { + contents = fs.readFileSync(file, 'utf8'); + } else { + contents = readSomeLines(file, options.numLines); + } + + var lines = contents.split('\n'); + var hasTrailingNewline = (lines[lines.length - 1] === ''); + if (hasTrailingNewline) { + lines.pop(); + } + shouldAppendNewline = (hasTrailingNewline || options.numLines < lines.length); + + head = head.concat(lines.slice(0, options.numLines)); + }); + + if (shouldAppendNewline) { + head.push(''); // to add a trailing newline once we join + } + return head.join('\n'); +} +module.exports = _head; |